The 34-year-old announced he was expecting with his wife Paige Price, just months after the pair got married in February.
Muniz revealed the happy news with a video posted to their YouTube channel, in which he and Price narrate a video of them dancing around in the countryside of Jackson, Wyoming.
“In the past four and a half years Paige and I have experienced so many incredible things together,” Muniz said. “We travelled the world and got to live out all these once-in-a-lifetime opportunities.
“While we still believe it’s the little moments in between the big ones that make you feel happy, nothing quite compares to the first time you hear the little one’s heartbeat.”
Meanwhile, Price explained candidly that the pair, who got engaged in November 2018, had struggled to conceive initially.
“When we found out we were expecting, I think we both were in a state of disbelief. We knew that we wanted this but we were told that our chances are not that great,” she said.
“The struggle of going to every doctor’s appointment made me feel less and less like a woman. I’m excited to say we’ve beat the odds and we’re officially 15 weeks along and counting.”
The video concludes with Muniz saying: “We’re both really excited for the future and we can’t wait to meet our little one.”
The happy news comes a month after Muniz reunited with his Malcolm in the Middle cast in honour of the show’s 20th anniversary.
Alongside Bryan Cranston, Muniz and the cast appeared over Zoom for a socially distanced catch-up, where they re-enacted the beloved comedy’s first episode.